Bb Major Scale

B flat is the black key between A and B. Start there and play B flat-C-D-E flat-F-G-A-B flat. E flat is the black key between D and E. You can find the half-step pairs D-E flat and A-B flat by pressing adjacent keys.

If you use E natural instead, D-E becomes a whole step and E-F a half step. The major-scale pattern would shift. That is why the E flat matters even though the scale already begins on a flat note.

The B flat major key signature has B flat and E flat. Compare F major: F-G-A-B flat-C-D-E. Those seven notes differ from B flat major by one pitch name, E versus E flat. Moving counterclockwise by a fifth on the circle of fifths adds the second flat.

The signature tells you the default spelling in notation. A written E natural can still occur in a piece centered on B flat; it needs a natural sign at that point.

Stack alternate scale notes. B flat-D-F is B flat major; F-A-C is F major; E flat-G-B flat is E flat major. All seven triads are B flat, Cm, Dm, E flat, F, Gm and A diminished.

Try B flat-E flat-F-B flat. All three major chords use only notes from the scale. Then play Gm-E flat-F-B flat. The new first chord gives the phrase a minor opening while the final B flat still establishes a major-key destination. Diatonic Chords explains the same stacking method in other keys.

G natural minor uses G-A-B flat-C-D-E flat-F, the same pitches. Play B flat-D-F-B flat over a low B flat, then G-B flat-D-G over a low G. The notes overlap but the chord and bass at rest have changed.

Play the scale upward, but pause on D. If the next key you choose is E flat, you have found the first of its two half steps. Finish A-B flat and you have found the other.